1. Field of the Invention
The present invention relates to an information record medium such as an optical disk of a high recording density type, which is capable of recording information such as video information, audio information and the like at a high density, and which is represented by a DVD (Digital Video or Versatile Disk). The present invention also relates to a recording apparatus for recording the information onto the information record medium, and a reproducing apparatus for reproducing the information from the information record medium.
2. Description of the Related Art
Conventionally, a so-called LD (Laser Disk) and a so-called CD (Compact Disk) are generalized as optical disks, on which information such as video information, audio information and the like is recorded.
On the LD or the like, the video information and the audio information are recorded together with time information indicating a time at which each information is to be reproduced with respect to a reproduction start position, which each LD or the like has, as a standard position. Thus, other than a general normal reproduction to reproduce the recorded information in the order of recording, various special reproductions are possible, such as a reproduction to extract and listen to an only desirable music out of a plurality of recorded musics, a reproduction to listen to the recorded musics in a random order and so on, in case of the CD, for example.
However, there is a problem that, according to the above mentioned LD or the like, a so-called interactive and variegated reproduction is not possible in which the audience can have a plurality of selection branches as for the video or audio information to be displayed or sound-outputted and in which the audience can select them to watch or listen to it.
Namely, for example, such an interactive reproduction as in a recent game or educational software cannot be performed in which, after a "question" is displayed, different displays, audio outputs and the like are selectively performed depending upon the content of "answer" inputted by the audience (e.g., if the "answer" is correct, the video image display or the audio sound output corresponding to the correct answer is performed, while, if the "answer" is incorrect, the video image display or the audio sound output corresponding to the incorrect answer is performed).
On the other hand, a proposal and a development are being made as for an interactive reproduction of the DVD, as an optical disk in which the memory capacity is improved by about ten times without changing the size of the optical disk itself as compared with the aforementioned conventional CD. It will be possible to make a DVD player perform a search operation and a scan operation (speedy watching and checking operation) in the same manner as a conventional LD player, from its constitutional property. Namely, the DVD player capable of performing the aforementioned interactive reproduction, will have dual functions i.e. both of a function of a reproducing apparatus for simply reproducing the information versus time in the same manner as the conventional LD player and a function of an apparatus for performing the interactive operation in the same manner as a personal computer or a game machine. Therefore, in case of performing the search operation or the scan operation with respect to the DVD capable of the aforementioned interactive reproduction, there will be a certain possibility that, before reproducing the "question", the information corresponding to its correct answer or its incorrect answer may be reproduced. This kind of reproduction is basically contrary to the intention of an author (i.e. a producer of the software) and is further undesirable for the audience (i.e. the user of the software) on the progress of the game or study.
However, there is no proposal or development made as for a DVD technique to prohibit such a reproduction, which is not intended by the author or not desired by the audience. Further, in the technical art of the interactive reproduction of the DVD which has the aforementioned dual functions, the actuality is such that a person having an ordinary skill in this art does not even recognize the problem or subject itself that the reproduction, which is not intended by the author or not desired by the audience upon searching or scanning, should not be performed.
The inventors of the present application have noticed this unknown problem prior to other people, and, in Japanese Patent Application No. Hei. 7-166025, has proposed (i) one reproduction method in which additional information including a reproduction prohibit information, which indicates a reproduction condition for each of predetermined data groups, is added in advance, so that the reproduction of the video data and the audio data, which follow the reproduction prohibit information, is allowed when an actual reproduction condition is judged to satisfy the reproduction condition indicated by the reproduction prohibit information (e.g., a condition that a predetermined reproduction procedure has been completed, a condition that a reproduction of "question" has been completed) by constantly monitoring the actual reproduction condition by the player (i.e. the reproducing apparatus), and (ii) another reproduction method in which additional information including a reproduction prohibit information, which indicates a standard value to permit a reproduction for each of predetermined data groups, is added in advance, and a reproduction permission level, which is determined in dependence on the actual reproducing operation condition with respect to the pertinent software, is given to each of the players (i.e. each of the reproducing apparatuses), so that the reproduction of the video data and the audio data, which follow the reproduction prohibit information, is allowed on the basis of the large or small relationship between the reproduction permission level and the standard value included in the reproduction prohibit information.
However, according to the above mentioned (i) and (ii) methods, the players should memorize the reproduction conditions and the sledding condition of reproduction. Especially, according to the (i) method, the player should monitor whether or not the reproduction of the "question" has been completed, and a specification bit in an internal register is set to "1" at a time of completion. After that, if there is a data group, which has the reproduction prohibit information indicating that the reproduction is to be allowed at the condition of this completion, the player performs a judgment whether the reproduction is allowed or prohibited according to the value of this internal register. Thus, if there are a plurality of branches in the software to be reproduced, there would be necessary a plurality of registers in the bit number corresponding to the number of the branches at least, in order to perform the judgment to allow the reproduction for each branch. On the other hand, according to the (ii) method, it is necessary to equip the player with a register which always stores the reproduction permission level in the non-volatile manner.
Further, according to these (i) and (ii) methods, since the reproduction prohibit information is added to each data group, the fact that the reproduction is prohibited is turned out after the optical pickup is actually moved to the position of the data group and reads out the information therefrom (namely, at a real time). Accordingly, if scanning is performed to the data group which reproduction is prohibited, (a) the scan operation will be suddenly stopped after the optical pickup is moved to this data group, (b) the optical pickup is returned to another data group which reproduction is not prohibited and the reproduction is started therefrom, after the optical pickup is moved once to this data group, (c) a jump is repeatedly performed again and again until finding another data group permitted to be reproduced. The above explained (a) operation is not basically suitable for the primary object of the scan operation, which is to reproduce the information at a position other than the present position on the optical disk. The above explained (b) operation is not basically suitable for the object of the scan operation, which is to move to a forward or backward position away from the present position, since the scan operation to stride over the prohibited portion is not possible in this case. The above explained (c) operation is operatively very inconvenient for the audience, since the interval, in which the reproduction is not performed while the scan operation is performed, becomes long in case that the portion prohibited to be reproduced is rather long. Especially, if such an operation is repeated at a vicinity of a first or last portion of the optical disk, scanning may be stopped as it is.
As explained above, the reproduction methods proposed by the present inventors are not perfect from a view point of the primary function of scanning.